Genome-Based Taxonomic Classification of Three Closely Related Genera, Gulosibacter, Pseudoclavibacter and ‘Zimmermannella’ in the Family Microbacteriaceae

The genera Pseudoclavibacter and ‘Zimmermannella’ (a later homotypic synonym of Pseudoclavibacter) are both described to accommodate Brevibacterium helvolum in 2004. The genus Gulosibacter, published in the same year, also shows a close similarity to the 16S rRNA gene sequence of genus ‘Zimmermannella’. To clarify the phylogenetic relationship of these genera, phylogenomic analysis has been performed on the representatives of three genera and five isolates from the poplar tree (poplar isolates) in the family Microbacteriaceae. The phylogenetic analyses based on genome and 16S rRNA gene sequences suggest that P. albus and ‘P. triregionum’ should belong to a novel genus in family Microbacteriaceae, which is supported by the results of AAI analysis. In the Phylogenomic tree, the five poplar isolates, P. caeni, and P. soli are grouped together to form one distinct clade from Pseudoclavibacter and Gulosibacter and other genera in the family Microbacteriaceae, suggesting that they should belong to a novel genus within the family Microbacteriaceae. The five poplar isolates are divided into two distinct groups from P. caeni and P. soli in the phylogenomic tree, suggesting that they should belong to two novel species, which is also supported by ANI analysis, phenotypic, and chemotaxonomic characteristics. Based on the data obtained, the following taxonomic proposals are made: (1) classification of the poplar isolates as Yuansilingia populi gen. nov. sp. nov. (type strain PZ6T = CFCC 11306T = LMG 31539T) and Yuansilingia affinipopuli sp. nov. (type strain is 13-3T = CFCC 11305T = LMG 42092T); (2) reclassification of Pseudoclavibacter caeni and Pseudoclavibacter soli as Yuansilingia caeni comb. nov. (type strain is KCTC 19773T = JCM 16921T = CFCC 10881T), Yuansilingia soli comb. nov. (type strain is KCTC 19255T = JCM 15058T = CFCC 10840T); (3) reclassification of P. albus as the type species of a novel genus, Urinibacter gen. nov., as Urinibacter albus comb. nov. (type strain IAM 14724T = NBRC 15616T = TISTR 1510T = CFCC 11178T), Pseudoclavibacter triregionum as Urinibacter triregionum comb. nov. (type strain is 125703-2019T (=R-76471T = LMG 31777T = CCUG 74796T).